What evidence is there that it was a flying accident when he was in the Royal Artillery.
Are you sure it's not Warden Point Isle of Sheppey ?
Warden Point, Isle of Sheppey had a Sound Mirror.
Regarding the Radar Early Warning (by wireless detection type means) that
enemy aircraft were approaching this phrase banded about on TV gives the wrong impression for 1940 and is totally misleading.
The 1940 Summer files at TNA, Kew, indicate that only 50% of aircraft approaching the English coast (over the Sea) were actually identified.
In other words 50% of the time our UK Defences only detected AIRCRAFT WERE APPROACHING our coasts, some of whom were FRIEND (returning bombers, fighters, coastal and other friendly aircraft) and/or FOE.
Despite all this misleading radar hype that we knew who were coming (we didn't always know), I suspect that this Sound Mirror might still be in use in 1940 and/or the installation would be guarded.
http://www.andrewgrantham.co.uk/soundmirrors/Even getting a Death Certificate might not explain, as some simply have "War Operations" for Cause of Death (which includes both friendly incidents and operational incidents and I don't always trust CWGC to be correct either, as official Unit records are occasionally contrary to CWGC), although a Death Certificate might give the nearest road name and say in a field, or so many miles and a compass bearing from a main town.
Sometimes, the only clue is the
Informant. However, I have discovered that ground civilians killed by RAF aircraft crashing on their houses have been reported by relatives, despite the aircrew deaths and a civilian aboard the aircraft (in the same incident) being reported by the RAF Unit who held the 'aircraft on charge' to the Registrar of the England & Wales Registration District.
If you get a Fighter Command grid reference let me know, I hold some Geographical Section General Staff maps for England (basically 1" OS, but with the Fighter Command grid overlay printed).
These should still be in ZOS 3 at TNA, Kew.
http://discovery.nationalarchives.gov.uk/results/r?_cr=ZOS%203&_dss=range&_sd=1939&_ed=1945&_ro=any&_st=advMark